1. Field of the Invention
This invention relates to a container end assembly and in one aspect to an improved container end construction for use on beverage containers and having an opening in said end covered by a length of removable tape. More particularly, this invention provides an improved tape closure for container ends which permits the clean opening of the container utilizing a tape closure.
The present invention provides an improved tape closure and has as an object thereof the leaving of a clean area surrounding the pour hole upon removal of the tape. This would be true of tape closures for container ends utilizing simply an exterior tape or a two-tape system, including an exterior tape and an interior sheet material situated circumjacent (over and surrounding) a preformed opening (i.e. a pour opening) in a container end portion.
The present invention provides a tape closure which when opened sufficiently to obtain access to the pour hole is not self-sealing and thus offers resistance to tampering which would not be possible of detection.
The present invention provides a tape closure for container ends which will withstand the internal pressure of carbonated beverages or other beverages where an internal pressure is developed.
The present invention provides an improved tape closure which is suitable for use with pressurized containers but which is easily removable as the force necessary for peeling the closure from the can end is relatively small compared to the force necessary to open score lines in the metal defining an opening. The present invention also reduces the amount of force necessary in a two-tape system for removing a tape closure.
2. Summary of the Present Invention
The present invention provides a container end assembly including a metallic can end of metal, i.e., tin plate or tin-free steel, aluminum or a composite of plastic and metal, formed with a pour opening, the exterior surface of the can end is coated with a layer of protective material, i.e. an enamel, and a tape is applied and adhered to the protective layer over the pour opening. The tape is provided with a heat activatable thermoplastic adhesive to secure the tape backing to the protective layer or coating on the can end. The adhesive is preferably bonded to the protective layer in a pattern to provide at one end of the pour opening a narrowing of the adhesive bond across the width of the tape to afford an initial reduced area for force concentration for the easy fracture of the protective layer to delaminate the protective layer in the area of the adhesive bond of the tape to separate the protective layer from the can end utilizing the high shear strength of the bonds between the tape and the protective layer and the protective layer and the can to withstand the pressure but relying on the weak peel strength of the bond between the protective layer and the can end to afford an easy open tape closure. In a two-tape system an interior sheet material is adhered to the inner surface of the can end circumjacent the pour opening and, in the area of the pour opening, the external tape is bonded by the adhesive to the interior sheet material to afford tearing of the interior sheet material at the edges of the pour opening as the exterior tape is peeled from the can end.
In the preferred embodiment the can end is formed from metal sheet stock, e.g., tin-free steel (TFS), coated with a first exterior layer for the can end which may be a lacquer or an enamel, and a second protective layer which may be a lacquer, enamel or a vinyl coating, is placed over the first layer, each of which is cured after being coated by heating to afford a releasable bond between the two layers. The exterior tape is then bonded to the second layer by an adhesive which bonds the two more firmly than the second layer bonds to the first. When the tape is removed to open the can, the bond between the two layers is ruptured and the second layer is peeled from the can end with the tape, exposing a clean pour opening.